1. Field of the Invention
This invention relates generally to the field of photovoltaic systems. More particularly, this invention relates to concentrated solar photovoltaic systems and parts thereof.
2. State of the Art
Terrestrial solar photovoltaic systems convert solar insolation into electrical energy using photovoltaic cells. The amount of electrical energy that a photovoltaic cell produces is proportional to the intensity of the insolation it receives and the surface area of the cell. Photovoltaic cells are typically made from either silicon or gallium arsenide. Silicon photocells are less efficient at converting solar insolation to electrical energy, and thus require a larger size and a greater number of cells to provide a required amount of electrical output. Gallium arsenide (GaAs) photovoltaic cells, by contrast, are more efficient at converting insolation to electrical energy, and thus require less surface area to achieve the same electrical output as their silicon counterparts, but are more expensive to manufacture.
Concentrating the insolation received by the GaAs photocell can effectively decrease costs by increasing the electrical output of the GaAs photocell. Typically, such concentration is realized by a large concentrator lens and a secondary optical element that cooperate to channel insolation to the GaAs photovoltaic cell. These components must be manufactured and assembled with tight tolerances in order to properly channel sunlight to the GaAs photocell.
The array of photocells typically heats up as the photocells absorb solar insolation and convert it to electrical energy. Moreover, despite the tight tolerances used in creating and assembling the components of the module, the concentrated light from the concentrator lenses can miss the secondary optical element (for example, when the module is not aligned to the incident angle of the solar insolation) and strike the base of the module which supports the photocells. This concentrated light can burn or otherwise damage the wiring of the photocell array and result in electrical shorts or other unwanted failures. In addition, condensation can form on the inside of the large concentrator lens of the module when the ambient temperature decreases (which typically occurs at night). Such condensation can drip down to the base of the module, collect there, and cause electrical shorts in the wiring of the photocell array during operation thereof. Moreover, given the high specific heat content of water, condensation at the base may also cause undesirable heating of the photocells and limit convection of heat away from the photocells during operation.